ACPI: scan: Make acpi_bus_get_device() clear return pointer on error
[platform/kernel/linux-rpi.git] / drivers / mfd / gateworks-gsc.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * The Gateworks System Controller (GSC) is a multi-function
4  * device designed for use in Gateworks Single Board Computers.
5  * The control interface is I2C, with an interrupt. The device supports
6  * system functions such as push-button monitoring, multiple ADC's for
7  * voltage and temperature monitoring, fan controller and watchdog monitor.
8  *
9  * Copyright (C) 2020 Gateworks Corporation
10  */
11
12 #include <linux/device.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
15 #include <linux/mfd/gsc.h>
16 #include <linux/module.h>
17 #include <linux/mutex.h>
18 #include <linux/of.h>
19 #include <linux/of_platform.h>
20 #include <linux/platform_device.h>
21 #include <linux/regmap.h>
22
23 #include <asm/unaligned.h>
24
25 /*
26  * The GSC suffers from an errata where occasionally during
27  * ADC cycles the chip can NAK I2C transactions. To ensure we have reliable
28  * register access we place retries around register access.
29  */
30 #define I2C_RETRIES     3
31
32 int gsc_write(void *context, unsigned int reg, unsigned int val)
33 {
34         struct i2c_client *client = context;
35         int retry, ret;
36
37         for (retry = 0; retry < I2C_RETRIES; retry++) {
38                 ret = i2c_smbus_write_byte_data(client, reg, val);
39                 /*
40                  * -EAGAIN returned when the i2c host controller is busy
41                  * -EIO returned when i2c device is busy
42                  */
43                 if (ret != -EAGAIN && ret != -EIO)
44                         break;
45         }
46
47         return 0;
48 }
49 EXPORT_SYMBOL_GPL(gsc_write);
50
51 int gsc_read(void *context, unsigned int reg, unsigned int *val)
52 {
53         struct i2c_client *client = context;
54         int retry, ret;
55
56         for (retry = 0; retry < I2C_RETRIES; retry++) {
57                 ret = i2c_smbus_read_byte_data(client, reg);
58                 /*
59                  * -EAGAIN returned when the i2c host controller is busy
60                  * -EIO returned when i2c device is busy
61                  */
62                 if (ret != -EAGAIN && ret != -EIO)
63                         break;
64         }
65         *val = ret & 0xff;
66
67         return 0;
68 }
69 EXPORT_SYMBOL_GPL(gsc_read);
70
71 /*
72  * gsc_powerdown - API to use GSC to power down board for a specific time
73  *
74  * secs - number of seconds to remain powered off
75  */
76 static int gsc_powerdown(struct gsc_dev *gsc, unsigned long secs)
77 {
78         int ret;
79         unsigned char regs[4];
80
81         dev_info(&gsc->i2c->dev, "GSC powerdown for %ld seconds\n",
82                  secs);
83
84         put_unaligned_le32(secs, regs);
85         ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4);
86         if (ret)
87                 return ret;
88
89         ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1,
90                                  BIT(GSC_CTRL_1_SLEEP_ADD),
91                                  BIT(GSC_CTRL_1_SLEEP_ADD));
92         if (ret)
93                 return ret;
94
95         ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1,
96                                  BIT(GSC_CTRL_1_SLEEP_ACTIVATE) |
97                                  BIT(GSC_CTRL_1_SLEEP_ENABLE),
98                                  BIT(GSC_CTRL_1_SLEEP_ACTIVATE) |
99                                  BIT(GSC_CTRL_1_SLEEP_ENABLE));
100
101
102         return ret;
103 }
104
105 static ssize_t gsc_show(struct device *dev, struct device_attribute *attr,
106                         char *buf)
107 {
108         struct gsc_dev *gsc = dev_get_drvdata(dev);
109         const char *name = attr->attr.name;
110         int rz = 0;
111
112         if (strcasecmp(name, "fw_version") == 0)
113                 rz = sprintf(buf, "%d\n", gsc->fwver);
114         else if (strcasecmp(name, "fw_crc") == 0)
115                 rz = sprintf(buf, "0x%04x\n", gsc->fwcrc);
116         else
117                 dev_err(dev, "invalid command: '%s'\n", name);
118
119         return rz;
120 }
121
122 static ssize_t gsc_store(struct device *dev, struct device_attribute *attr,
123                          const char *buf, size_t count)
124 {
125         struct gsc_dev *gsc = dev_get_drvdata(dev);
126         const char *name = attr->attr.name;
127         long value;
128
129         if (strcasecmp(name, "powerdown") == 0) {
130                 if (kstrtol(buf, 0, &value) == 0)
131                         gsc_powerdown(gsc, value);
132         } else {
133                 dev_err(dev, "invalid command: '%s\n", name);
134         }
135
136         return count;
137 }
138
139 static struct device_attribute attr_fwver =
140         __ATTR(fw_version, 0440, gsc_show, NULL);
141 static struct device_attribute attr_fwcrc =
142         __ATTR(fw_crc, 0440, gsc_show, NULL);
143 static struct device_attribute attr_pwrdown =
144         __ATTR(powerdown, 0220, NULL, gsc_store);
145
146 static struct attribute *gsc_attrs[] = {
147         &attr_fwver.attr,
148         &attr_fwcrc.attr,
149         &attr_pwrdown.attr,
150         NULL,
151 };
152
153 static struct attribute_group attr_group = {
154         .attrs = gsc_attrs,
155 };
156
157 static const struct of_device_id gsc_of_match[] = {
158         { .compatible = "gw,gsc", },
159         { }
160 };
161 MODULE_DEVICE_TABLE(of, gsc_of_match);
162
163 static struct regmap_bus gsc_regmap_bus = {
164         .reg_read = gsc_read,
165         .reg_write = gsc_write,
166 };
167
168 static const struct regmap_config gsc_regmap_config = {
169         .reg_bits = 8,
170         .val_bits = 8,
171         .cache_type = REGCACHE_NONE,
172         .max_register = GSC_WP,
173 };
174
175 static const struct regmap_irq gsc_irqs[] = {
176         REGMAP_IRQ_REG(GSC_IRQ_PB, 0, BIT(GSC_IRQ_PB)),
177         REGMAP_IRQ_REG(GSC_IRQ_KEY_ERASED, 0, BIT(GSC_IRQ_KEY_ERASED)),
178         REGMAP_IRQ_REG(GSC_IRQ_EEPROM_WP, 0, BIT(GSC_IRQ_EEPROM_WP)),
179         REGMAP_IRQ_REG(GSC_IRQ_RESV, 0, BIT(GSC_IRQ_RESV)),
180         REGMAP_IRQ_REG(GSC_IRQ_GPIO, 0, BIT(GSC_IRQ_GPIO)),
181         REGMAP_IRQ_REG(GSC_IRQ_TAMPER, 0, BIT(GSC_IRQ_TAMPER)),
182         REGMAP_IRQ_REG(GSC_IRQ_WDT_TIMEOUT, 0, BIT(GSC_IRQ_WDT_TIMEOUT)),
183         REGMAP_IRQ_REG(GSC_IRQ_SWITCH_HOLD, 0, BIT(GSC_IRQ_SWITCH_HOLD)),
184 };
185
186 static const struct regmap_irq_chip gsc_irq_chip = {
187         .name = "gateworks-gsc",
188         .irqs = gsc_irqs,
189         .num_irqs = ARRAY_SIZE(gsc_irqs),
190         .num_regs = 1,
191         .status_base = GSC_IRQ_STATUS,
192         .mask_base = GSC_IRQ_ENABLE,
193         .mask_invert = true,
194         .ack_base = GSC_IRQ_STATUS,
195         .ack_invert = true,
196 };
197
198 static int gsc_probe(struct i2c_client *client)
199 {
200         struct device *dev = &client->dev;
201         struct gsc_dev *gsc;
202         struct regmap_irq_chip_data *irq_data;
203         int ret;
204         unsigned int reg;
205
206         gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL);
207         if (!gsc)
208                 return -ENOMEM;
209
210         gsc->dev = &client->dev;
211         gsc->i2c = client;
212         i2c_set_clientdata(client, gsc);
213
214         gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client,
215                                        &gsc_regmap_config);
216         if (IS_ERR(gsc->regmap))
217                 return PTR_ERR(gsc->regmap);
218
219         if (regmap_read(gsc->regmap, GSC_FW_VER, &reg))
220                 return -EIO;
221         gsc->fwver = reg;
222
223         regmap_read(gsc->regmap, GSC_FW_CRC, &reg);
224         gsc->fwcrc = reg;
225         regmap_read(gsc->regmap, GSC_FW_CRC + 1, &reg);
226         gsc->fwcrc |= reg << 8;
227
228         gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter,
229                                                    GSC_HWMON);
230         if (IS_ERR(gsc->i2c_hwmon)) {
231                 dev_err(dev, "Failed to allocate I2C device for HWMON\n");
232                 return PTR_ERR(gsc->i2c_hwmon);
233         }
234
235         ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq,
236                                        IRQF_ONESHOT | IRQF_SHARED |
237                                        IRQF_TRIGGER_FALLING, 0,
238                                        &gsc_irq_chip, &irq_data);
239         if (ret)
240                 return ret;
241
242         dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n",
243                  gsc->fwver, gsc->fwcrc);
244
245         ret = sysfs_create_group(&dev->kobj, &attr_group);
246         if (ret)
247                 dev_err(dev, "failed to create sysfs attrs\n");
248
249         ret = devm_of_platform_populate(dev);
250         if (ret) {
251                 sysfs_remove_group(&dev->kobj, &attr_group);
252                 return ret;
253         }
254
255         return 0;
256 }
257
258 static int gsc_remove(struct i2c_client *client)
259 {
260         sysfs_remove_group(&client->dev.kobj, &attr_group);
261
262         return 0;
263 }
264
265 static struct i2c_driver gsc_driver = {
266         .driver = {
267                 .name   = "gateworks-gsc",
268                 .of_match_table = gsc_of_match,
269         },
270         .probe_new      = gsc_probe,
271         .remove         = gsc_remove,
272 };
273 module_i2c_driver(gsc_driver);
274
275 MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
276 MODULE_DESCRIPTION("I2C Core interface for GSC");
277 MODULE_LICENSE("GPL v2");